The malarial parasite alters and affects the host erythrocyte. Several new parasite-induced compartments are observed in the infected erythrocyte and parasite proteins are localized to these various compartments. It is not known how the parasite can transport and target proteins to locations beyond its own plasma membrane. Ultrastructural studies and immunogold localization were carried out to learn more about how the parasite transports and targets proteins to the host erythrocyte. In particular the export of the 93 kDa Plasmodium chabaudi protein, which is associated with the host erythrocyte membrane, was examined. Studies using Brefeldin A, an inhibitor of the secretory pathway, indicated that some exported Plasmodium proteins utilize an alternative secretory pathway. These exported proteins do transit through the endoplasmic reticulum and Golgi, but are targeted to a new Brefeldin A-induced compartment. From this new compartment the proteins are probably secreted into the parasitophorous vacuole, where they become associated with tubovesicular structures derived from the parasitophorous vacuolar membrane. The targeting and sorting of exported parasite proteins may occur at the level of parasitophorous vacuolar membrane.